function Control() {
  this.show();
  this.layout();
}
Control.prototype.show = function () {
  var div = document.createElement('div');
  document.body.appendChild(div);
  div.style.backgroundColor = this.fillColor;
  div.style.position = 'absolute';
  this.ele = div;
};
Control.prototype.layout = function () {};
Control.windowResized = function () {
  //构造函数本身也是对象
  //给构造函数添加一些属性  记录常用的值
  //记录了窗口的宽高
  Control.cWidth = document.documentElement.clientWidth;
  Control.cHeight = document.documentElement.clientHeight;
  Control.cRadius = Math.min(Control.cWidth, Control.cHeight) / 2;
  Control.c_x = Control.cWidth / 2;
  Control.c_y = Control.cHeight / 2;
};
//调用方法 添加属性 设置常用值
Control.windowResized();
